noise in transmission just prior to shifting
 

I've headed over this way from the z71 forums to see if someone here can shed some light on an issue I'm having. I've searched several different terms but nothing is coming up related to the problem I'm having. My truck is a 2003 Suburban LT with the 5.3 / 4L60E combo. 185k miles, though all systems are functioning well.

Here's the deal.

During the summer when my truck is "cold" i.e. early morning start, the transmission would make a "whooshing" or "shhhhhhh" noise just before shifting, though it shifts firm and engages smoothly. In fall, when it is legitimately cold in the morning, that "whoosh" has turned into a defined mechanical noise with a sharp start "ghhhh" rather than "shhh" just before shifting. It only does this for 2-3 shifts before the transmission is warm, and won't do it if I let the truck idle for 5 - 10 min. first. However, with the significant increase in volume and "tone" of the noise, I want to address it ASAP before winter.

Any ideas, suggestions, etc.? Technical answers are fine, I do all my own vehicle work and am quite competent at diagnosing systems, though knowing what I'm looking for would be nice. My guess is a transmission servo changing the fluid path before the gear change is responsible but I don't know if those can wear out or if they even can cause noise when they do.

Thanks in advance.

fluid
 

When was the fluid last changed?

8k miles ago, pan drop, new filter. Have another change non-pan drop waiting to go.

Did you get anywhere with this? My 2003 Suburban is doing exactly what you describe.

I'll be darned. Forgot all about this thread. I usually try to post my solutions, but this problem I'd posted all over the place.

Here goes. I did not try to narrow it down to a specific solenoid, but I'm betting it was the 1-2 and 2-3 solenoids. I had a bunch of miles and the solenoids were pretty cheap so I did them all( about $115). I got mine from transmissionpartsusa.com. I've used em for a couple projects for a number of years and don't have any complaints. It took almost no time to swap the solenoids no manual or diagram. There are some tricky fasteners but nothing bad.

Also, if you have extra money laying around, get a corvette servo to install while you have your pan down. Even more money laying around? Get the Blackbear tune and have them straighten out the shifting patterns. You can performance tune too, but I did it mostly for the shifting and it was well worth it. No more downshifting to 4500 RPM on a mild incline then immediately back up into third.

Wow, thanks a lot for replying! I'll get these solenoid on order. If this works, you'll be my hero!

You might check, but usually you can pick up a filter and gasket for just a couple buck with that order. Your fluid will probably run another $75. Good luck, I'm virtually certain that will solve your problem.

Problem Solved!
 

Changed the solenoids and the noise is gone! Thanks so much for your original post! Along with new intake manifold gaskets, my Suburban runs like a swiss watch.

Thanks for the feedback. Will help someone in the future. :cool:

Just an FYI, I replaced the 1-2 and 3-4 shift solenoids and I'm still having this same issue. I'm wondering which solenoid in particular caused the noise. I'll try to update once I determine it.
FF6